Add KRB5_TRACE test case

In t_general.py, run kinit with KRB5_TRACE enabled and make sure we
see some basic strings in the resulting file.

https://github.com/krb5/krb5/commit/77e492489beadd3869c82775903bd2649ccf3f8f
Commit By: ghudson
Revision: 25821
Changed Files:
U   trunk/src/tests/t_general.py